High resolution NMR studies of metabolism in wild-type and high osmolarity mutants of Saccharomyces cerevisiae

Author

Fernet, Marie-Dominique Fabiola

Date

1992

Degree

Master of Science

Abstract

High resolution $\sp{13}$C NMR was used to study the formation of metabolites from (1-$\sp{13}$C) -labelled glucose by wild-type and HOG (high osmolarity glycerol response) mutants of the yeast Saccharomyces cerevisiae after transfer to media containing 400 mM NaCl. Time course spectroscopy showed that the major end-products were (2- $\sp{13}$C) -ethanol, (1-$\sp{13}$C) -glycerol and in much lower concentration, (2-$\sp{13}$C) -acetate. High osmolarity increased ethanol, glycerol and acetate production. Additional labeling incorporated in trehalose, glycogen or glutamate was similar in all strains. In contrast to the wild-type, the hog1 mutant decreased glycerol and acetate production in normal and hyperosmotic media, whereas the hog2 mutant only reduced glycerol synthesis under high osmolarity. The decreases in osmolarity-induced glycerol synthesis were quantitatively additive in the hog1 hog2 mutant. Effects of the hog1 and hog2 mutations on yeast fermentation suggest that the HOG1 and HOG2 genes regulate or influence different aspects in fermentation metabolism.